Dendritic cells are potent and essential initiators of immune responses. This quality has begun to be harnessed for experimental use in human disorders and animal models. Though much information is coming to light about the nature of dendritic cell interactions with T and B cells, this remains a rapidly evolving field. Using stably marked, cultured dendritic cells, persistent survival and expansion of donor cells have been noted in vivo after I.V. administration. These expanding cells have been identified as B cells which represent a small (1 %) contaminating population in bone marrow derived dendritic cells, but which expand significantly after dendritic cell transfer to animals. Experiments will be performed to determine the nature of dendritic cell-B cell interactions which allow for both the survival and proliferation of these B-cells in vitro and in vivo. Specifically, the role of antigen will be dissected in this phenomenon. The potential impact of this donor B-cell expansion on concurrent T cell responses will be examined as well. The Kappler/Marrack laboratory is an ideal and stimulating environment in which to launch a research career. This laboratory, as well as the University of Colorado community, and the Department of Pediatrics have been very supportive of my goal to initiate a successful career as a physician scientist. As a pediatric hematologist/oncologist , I have the good fortune of working in a field that is tied closely to the basic sciences, and one that will benefit greatly from translational endeavors. My near term career path will involve ongoing basic research and study in order to improve my ultimate scientific productivity.